Convention bounces – the verdict

Last week, I took a look at the immediate bounce enjoyed by Republican presidential nominee Donald Trump. Using the four poll released between the two conventions, we saw that Trump’s bounce was 4.5 points. Now that the Democratic convention has come and gone, it’s time to look at the bounce Democratic presidential nominee Hillary Clinton has experienced. I want to look at it from two perspectives.

First, how have the numbers moved considering just the Democratic Convention. In order to analyze this, I use just the polls I cited in calculating Trump’s bounce, only this time, they’ll be the ‘before’ picture rather than the ‘after’ picture. One of the four, Gravis Marketing, hasn’t yet polled post-DNC. So, the calculations are based on the other three – CBS News, CNN/ORC, and LA Times/USC. The following table shows Clinton’s bounce was substantial.

Polling firm

Before

After

Bounce

Averages:

Trump +2.7

Clinton +4.3

Clinton +7.0

CBS News

Trump +1

Clinton +6

Clinton +7

CNN/ORC

Trump +3

Clinton +9

Clinton +12

LA Times/USC

Trump +4

Trump +2

Clinton +2

Seven points is quite an improvement. However, we must remember that the ‘before’ numbers are at the height of Trump’s bounce. A more useful perspective spans both conventions, and that’s what I do in the second table. To qualify for this dataset, polling firms must have conducted a Trump vs. Clinton poll in the week or so before the GOP Convention and then again after the close of the Democratic Convention. Six such firms meet that criterion, and they show Clinton did win the bounce gain, but not by as much as in the previous example. Her lead before the RNC, according to these six polls, was 0.7%. Now, it is 4.2%, a bump of 3.5%. And that figure represents, as closely as polls can do, the true convention bounce as calculated over both conventions.

Polling firm

Before RNC

After DNC

True Bounce

Averages:

Clinton +0.7

Clinton +4.2

Clinton +3.5

Economist/YouGov

Clinton +4

Clinton +3

Trump +1

LA Times/USC

Trump +1

Trump +2

Trump +1

CBS News

Tie

Clinton +6

Clinton +6

CNN/ORC

Clinton +7

Clinton +9

Clinton +2

NBC News/Survey Monkey

Clinton +1

Clinton +8

Clinton +7

Rasmussen

Trump +7

Clinton +1

Clinton +8

These conclusions, of course, do not arise from an exact science. There are plenty of forces at work that may be affecting the numbers outside of the conventions – such as Trump’s travails after stepping into it regarding the Khan family. And other polls are still to be conducted by firms not included in this table. That said, I think Clinton +3.5 is probably a pretty good assessment of how the two nominees emerged from their conventions. Another important aspect of this to remember is that the DNC followed the RNC, and, therefore, Clinton’s standing is fresher in the minds of voters. As a result, some additional settling (ie: tightening) in the race is likely in store as we move away from the fervor generated by the conventions.